Question

There is a bag with only red marbles and blue marbles.

The probability of randomly choosing a red marble is 5/8

There are 72 marbles in total in the bag and each is equally likely to be chosen.

Work out how many red marbles there must be.

Answer 1

Given,

Total number of marbles in the bag = 72

Probability of choosing a red marble = 5/8

To FInd,

The number of red marbles.

Solution,

Let us assume the number of red marbles in the bag be x

So,

probability of choosing a red marble = x/72

Also, it is given to be 5/8

So, on comparing these two probabilities we get

x/72 = 5/8

x = 45

Hence, there are 45 red balls in the bag.

Answer 2

Answer:

there is a bag with red and blue marbles.

Step-by-step explanation:

Explanation :

Given that ,there is a bag with red marbles  and blue marbles.

Total number of marbles in the  bag is 72  and the

probability of choosing a red marble = 5/8 .

So , we need to find the number of red marbles.

Step 1:

x be the number of red marbles in the bag

∴ probablility  of getting a red marble = $\frac{x}{72}$

but , it is given  in the question that probability of randomly choosing a red marbles is 5/8.

So , on comparing both the probabilities

we get ,

x/72 = 5/8

⇒x ×8 = 5×72

⇒x= 360/8

⇒x = 45

Final answer:

Hence ,the number of red marbles in the bag is 45.